I have an Internet router, which uses NAT for IPv4, same as everyone else. If I want to punch a hole through for something like RDP or SSH, I have to use unique port numbers because I only have one Internet-facing IP address. Because there are only 3 billion IPv4 addresses for the whole World, all of them are regularly scanned by Bad People for open ports, making this RISKY.

I also have IPv6 enabled on it. No NAT. If I want to punch a hole through for RDP or SSH, I can use the standard ports because each device has a unique Internet-facing IP address. My router alone has 2^64 (millions of trillions) of unique addresses, of which a random 5 or 6 have been allocated. There is no way anyone ever is going to be able to scan these. I can SAFELY open standard port numbers and not have to worry about drive-by attacks.

THERE IS NO OTHER DIFFERENCE.

The router works the same, the firewall works the same, the Internet works the same, the GUI is the same. IT IS ALL THE SAME!

NAT is not magic. It is not a firewall. It is not necessary. It is not beneficial.